how to fix P0300 misfire code on my Toyota Tacoma N300 (2016-Present)

Solution

1. Preparation

• Gather tools: OBD-II scanner, multimeter, socket set, torque wrench, fuel pressure gauge, and vacuum gauge.
• Ensure the vehicle is parked on a level surface and the engine is cool.

2. Replace Spark Plugs

• Sub-steps:
  1. Disconnect the negative battery terminal.
  2. Remove the engine cover if applicable.
  3. Using a socket, remove the spark plugs. Inspect for wear or damage.
  4. Install new spark plugs (OEM recommended) and torque them to manufacturer specifications (typically around 13-15 ft-lbs).
  5. Reattach the engine cover.

3. Inspect and Replace Ignition Coils

• Sub-steps:
  1. Remove the ignition coil connectors.
  2. Unscrew the ignition coils from the engine using the appropriate socket.
  3. Test each coil with a multimeter for proper resistance; replace any that are out of spec.
  4. Install new ignition coils, ensuring they are secured and connectors are firmly attached.

4. Check and Clean Fuel Injectors

• Sub-steps:
  1. Relieve fuel pressure by removing the fuel pump fuse and starting the engine until it stalls.
  2. Disconnect fuel injector connectors and remove the fuel rail.
  3. Inspect and clean the injectors using a fuel injector cleaner spray or ultrasonic cleaning.
  4. Reinstall the fuel rail and reconnect the injectors.

5. Inspect for Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses connected to the intake manifold.
  2. Use a vacuum gauge to check for leaks; a low reading indicates a leak.
  3. Replace any damaged hoses or gaskets.

6. Test Fuel Pressure

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail service port.
  2. Turn the ignition to the "ON" position without starting the engine and check the pressure; it should meet the manufacturer’s specifications (typically around 50-60 psi).
  3. If the pressure is low, inspect the fuel pump and filter for issues.